U.S. patent application number 11/444408 was filed with the patent office on 2006-12-07 for scanning type inkjet image forming apparatus.
This patent application is currently assigned to SAMSUNG Electronics Co., Ltd. Invention is credited to Jung-hwan Kim, Sang-mi Oh.
Application Number | 20060274101 11/444408 |
Document ID | / |
Family ID | 37493689 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060274101 |
Kind Code |
A1 |
Oh; Sang-mi ; et
al. |
December 7, 2006 |
Scanning type inkjet image forming apparatus
Abstract
A scanning type inkjet image forming apparatus. The inkjet image
forming apparatus includes a printhead having at least one nozzle
group having a plurality of nozzles, a driving unit to drive the
plurality of nozzles to print an image, and a controller to
generate control signals to drive the driving unit so as to drive
the nozzles of the at least one nozzle group and to drive the
nozzles in a plurality of nozzle blocks time-divisionally, wherein
the controller drives the nozzles of the at least one nozzle group
and the nozzles of the nozzle blocks in the same direction.
Inventors: |
Oh; Sang-mi; (Suwon-si,
KR) ; Kim; Jung-hwan; (Seoul, KR) |
Correspondence
Address: |
STANZIONE & KIM, LLP
919 18TH STREET, N.W.
SUITE 440
WASHINGTON
DC
20006
US
|
Assignee: |
SAMSUNG Electronics Co.,
Ltd
|
Family ID: |
37493689 |
Appl. No.: |
11/444408 |
Filed: |
June 1, 2006 |
Current U.S.
Class: |
347/15 |
Current CPC
Class: |
B41J 2/205 20130101 |
Class at
Publication: |
347/015 |
International
Class: |
B41J 2/205 20060101
B41J002/205 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 1, 2005 |
KR |
2005-46740 |
Claims
1. An inkjet image forming apparatus, comprising: a printhead
having at least one nozzle group, and the nozzle group having a
plurality of nozzles, a driving unit to drive the plurality of
nozzles to print an image; and a controller to generate control
signals to drive the driving unit so as to drive the plurality of
nozzles of the at least one nozzle group and to time-divisionally
drive the nozzles in the at least one nozzle group in a plurality
of nozzle blocks, wherein the controller drives the nozzles of the
at least one nozzle group and the nozzles of the nozzle blocks in
the same direction.
2. The inkjet image forming apparatus of claim 1, further
comprising: a carriage on which the printhead is mounted to move in
a main scanning direction and to print an image, wherein the
printhead prints to the same printed area moving two or more times
repeatedly.
3. The inkjet image forming apparatus of claim 2, wherein the
controller generates control signals to determine an order in which
to drive the nozzles of the at least one nozzle group and the
nozzles of the nozzle blocks so that patterns printed by driving
the nozzles of the at least one nozzle group and patterns printed
by driving the nozzles of the nozzle blocks form slanted lines
having the same slope.
4. The inkjet image forming apparatus of claim 3, wherein the
controller generates control signals so that the patterns printed
by driving the nozzles of the nozzle blocks are symmetrical with
one another based on the patterns printed by driving the nozzles of
the at least one nozzle group.
5. The inkjet image forming apparatus of claim 4, wherein the
controller generates control signals so that the nozzles of the at
least one nozzle group are driven in one direction when the
printhead performs a first printing operation.
6. The inkjet image forming apparatus of claim 1, wherein the
driving unit comprises a thermal driving type driving unit.
7. The inkjet image forming apparatus of claim 1, wherein the
driving unit comprises a piezoelectric type driving unit.
8. The inkjet image forming apparatus of claim 1, wherein the
nozzles of the at least one nozzle group are arranged in parallel
with a subsidiary scanning direction.
9. The inkjet image forming apparatus of claim 1, wherein the at
least one nozzle group is disposed in a zigzag pattern in a
subsidiary scanning direction.
10. An inkjet image forming apparatus, comprising: at least one
nozzle group having a plurality of nozzles that are arrangeable in
two or more nozzle blocks; a printhead having the at least one
nozzle group; a driving unit to drive the plurality of nozzles to
print an image; and a controller to generate control signals to
drive the driving unit so as to drive the plurality of nozzles of
the at least one nozzle group and to drive the nozzles in the two
or more nozzle blocks time-divisionally, wherein the controller
drives the nozzles of the at least one nozzle group and the nozzles
of the two or more nozzle blocks in the same direction.
11. The inkjet image forming apparatus of claim 10, further
comprising: a carriage on which the printhead is mounted to move in
a main scanning direction and to print an image, wherein the
printhead prints to the same printed area moving two or more times
repeatedly.
12. The inkjet image forming apparatus of claim 11, wherein the
controller generates control signals to sequentially drive the
nozzles of the at least one nozzle group from a first nozzle to an
N-th nozzle during a first printing operation, and to drive one of
the two or more nozzle blocks and then to drive the other of the
two or more nozzle blocks during a second printing operation.
13. The inkjet image forming apparatus of claim 11, wherein the
controller generates control signals to determine an order in which
to drive the nozzles of the at least one nozzle group and the
nozzles of the two or more nozzle blocks so that patterns printed
during the first printing operation and patterns printed during the
second printing operation form slanted lines having the same
slope.
14. An inkjet image forming apparatus, comprising: a first nozzle
group having N nozzles; a second nozzle group disposed to be
parallel with the first nozzle group and having L nozzles; a
printhead having at least the first nozzle group and the second
nozzle group; a driving unit to drive the N nozzles and the L
nozzles to print an image; and a controller to generate control
signals to drive the driving unit so as to drive the nozzles N and
L of the first and second nozzle groups and to drive the N nozzles
and the L nozzles in a plurality of nozzle blocks
time-divisionally, wherein the controller drives the nozzles N and
L of the first and second nozzle groups and the nozzles of the
plurality of nozzle blocks in the same direction.
15. The inkjet image forming apparatus of claim 14, further
comprising: a carriage on which the printhead is mounted to move in
a main scanning direction and to print an image, wherein the
printhead prints to the same printed area moving two or more times
repeatedly.
16. The inkjet image forming apparatus of claim 15, wherein the
controller generates control signals to drive the driving unit so
as to sequentially drive the nozzles N of the first nozzle group
from a first nozzle to an N-th nozzle, and to drive the nozzles L
of the second nozzle group in M nozzle blocks.
17. The inkjet image forming apparatus of claim 16, wherein the
controller generates control signals to determine an order in which
to drive the nozzles N of the first nozzle group and the nozzles L
of the M nozzle blocks in the second nozzle group so that patterns
printed by driving the nozzles N of the first nozzle group and
patterns printed by driving the nozzles L of the M nozzle blocks in
the second nozzle group form slanted lines having the same
slope.
18. The inkjet image forming apparatus of claim 14, wherein the
nozzles N and L of the first and second nozzle groups are disposed
to be parallel in a subsidiary scanning direction.
19. The inkjet image forming apparatus of claim 14, wherein the
first and second nozzle groups are disposed in a zigzag pattern in
a subsidiary scanning direction.
20. An inkjet image forming apparatus, comprising: a print head
unit having a plurality of nozzles extending along a first axis
thereof and to reciprocate over a print medium; and a controller to
control the print head unit to perform a first printing operation
to sequentially eject ink from the plurality of nozzles in a line
in a first direction along the first axis, and to control the print
head unit to perform a second printing operation to sequentially
eject ink from at least a first block of the plurality of nozzles
and at least a second block of the plurality of nozzles in the line
in the first direction along the first axis.
21. The inkjet image forming apparatus of claim 20, wherein the
controller controls the first printing operation while the print
head unit reciprocates a first time over the print medium, and the
controller controls the second printing operation while the print
head unit reciprocates a second time over the print medium.
22. The inkjet image forming apparatus of claim 20, wherein the
controller controls the print head unit to print from a first end
thereof to a second end thereof during the first printing operation
in the first direction, and controls the print head unit to print
using the at least one first block which is disposed closest to the
second end of the print head unit and then the at least one first
block which is disposed closest to the first end of the print head
unit in the first direction.
23. The inkjet image forming apparatus of claim 20, wherein the
controller controls the print head unit to print to a print area
two or more times.
24. The inkjet image forming apparatus of claim 20, wherein the
print medium is stopped during the first and second printing
operations.
25. The inkjet image forming apparatus of claim 20, wherein the
first print operation creates a first line having a predetermined
slope at a first location on the print medium, and the second
printing operation creates a second line having the predetermined
slope on a first side of the first line and a third line having the
predetermined slope on a second side of the first line.
26. The inkjet image forming apparatus of claim 20, wherein the
print head unit comprises a plurality of head chips.
27. The inkjet image forming apparatus of claim 20, wherein the
print head unit comprises a plurality of rows of nozzles
corresponding to a plurality of different color inks.
28. The inkjet image forming apparatus of claim 20, wherein the
plurality of nozzles are arranged in one of a parallel line
arrangement and a zig-zag arrangement.
29. The inkjet image forming apparatus of claim 20, wherein the
first printing operation corresponds to a first reciprocation over
the print medium, and the second printing operation corresponds to
a second reciprocation over the print medium.
30. An inkjet image forming apparatus, comprising: a print head
unit having a plurality of nozzles that are divisible into at least
a first nozzle block and a second nozzle block extending along a
first axis thereof and to reciprocate over a print medium; and a
controller to control the print head unit to perform a first
printing operation to sequentially eject ink from the first nozzle
block and the second nozzle block in a line in a first direction
along the first axis, and to control the print head unit to perform
a second printing operation to sequentially eject ink from the
second nozzle block and the first nozzle block in the line in the
first direction along the first axis.
31. An inkjet image forming apparatus, comprising: a print head
unit having a plurality of nozzles; and a controller to reciprocate
the print head unit in a predetermined reciprocation direction over
a print medium, to control the print head unit to perform a first
print operation using a first sequence of the plurality of nozzles
in a predetermined ejection direction, and to control the print
head unit to perform a second print operation using a second
sequence of the plurality of nozzles in the same predetermined
ejection direction.
32. An inkjet image forming apparatus, comprising: a print head
unit including at least a first nozzle group and a second nozzle
group each having corresponding pluralities of nozzles extending
along a length pf the print head unit; and a controller to
reciprocate the print head unit over a print medium, to control the
first nozzle group to eject ink in a first sequence of the
plurality of nozzles in a predetermined sequence direction of the
print head unit, to control the second nozzle group to eject ink in
a second sequence of the corresponding plurality of nozzles in the
predetermined sequence direction of the print head unit, and the
first sequence is different from the second sequence.
33. The inkjet image forming apparatus of claim 32, wherein the
controller controls the first group to eject ink from the nozzles
sequentially along the length of the print head unit in the
predetermined sequence direction one by one, and the controller
controls the second group to eject ink from the nozzles in
sequential blocks in the predetermined sequence direction one by
one.
34. The inkjet image forming apparatus of claim 33, wherein the
first and second nozzle groups eject ink simultaneously.
35. The inkjet image forming apparatus of claim 32, wherein the
controller controls the first nozzle group of the print head unit
to print from a first end of the print head unit to a second end of
the print head unit during a first printing operation in the
predetermined sequence direction, and controls the second group of
the print head unit to print using the at least one first block
which is disposed closest to the second end of the print head unit
and then the at least one first block which is disposed closest to
the first end of the print head unit in the predetermined sequence
direction.
36. The inkjet image forming apparatus of claim 32, wherein the
controller controls the print head unit to print to a print area
two or more times.
37. The inkjet image forming apparatus of claim 32, wherein the
print medium is stopped during the ejection of ink from the first
and second nozzle groups.
38. The inkjet image forming apparatus of claim 32, wherein the
first nozzle group creates a first line having a predetermined
slope at a first location on the print medium, and the second
nozzle group creates a second line having the predetermined slope
on a first side of the first line and a third line having the
predetermined slope on a second side of the first line.
39. The inkjet image forming apparatus of claim 32, further
comprising: one or more transfer rollers to repeatedly convey and
stop the print medium a predetermined distance before the first and
second nozzle groups eject ink thereto during printing according to
one or more control signals received from the controller.
40. A method of controlling an inkjet image forming apparatus
including a print head unit having a plurality of nozzles, the
method comprising: reciprocating the print head unit in a
predetermined reciprocation direction over a print medium;
controlling the print head unit to perform a first print operation
using a first sequence of the plurality of nozzles in a
predetermined ejection direction; and controlling the print head
unit to perform a second print operation using a second sequence of
the plurality of nozzles in the same predetermined ejection
direction.
41. A method of controlling an inkjet image forming apparatus
including a print head unit having a plurality of nozzles that are
divisible into at least a first nozzle block and a second nozzle
block extending along a first axis thereof and to reciprocate over
a print medium, the method comprising: controlling the print head
unit to perform a first printing operation to sequentially eject
ink from the first nozzle block and the second nozzle block in a
line in a first direction along the first axis; and controlling the
print head unit to perform a second printing operation to
sequentially eject ink from the second nozzle block and the first
nozzle block in the line in the first direction along the first
axis.
42. A computer readable medium containing executable code to
control an inkjet image forming apparatus including a print head
unit having a plurality of nozzles, the method comprising: a first
executable code to reciprocate the print head unit in a
predetermined reciprocation direction over a print medium; a second
executable code to control the print head unit to perform a first
print operation using a first sequence of the plurality of nozzles
in a predetermined ejection direction; and a third executable code
to control the print head unit to perform a second print operation
using a second sequence of the plurality of nozzles in the same
predetermined ejection direction.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Korean Patent
Application No. 10-2005-0046740, filed on Jun. 1, 2005, in the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present general inventive concept relates to an inkjet
image forming apparatus, and more particularly, to a scanning type
inkjet image forming apparatus which performs a printing operation
with high resolution.
[0004] 2. Description of the Related Art
[0005] A scanning type inkjet image forming apparatus forms an
image by ejecting ink from a printhead that reciprocates in a
direction that is perpendicular to a feeding direction of a print
medium while being spaced apart from a top side of the printing
medium by a predetermined gap. A printing quality is a very
important factor in the scanning type inkjet image forming
apparatus. Japanese Patent Laid-open Publication No. 2001-232781
describes a conventional inkjet image forming apparatus that
enhances printing quality.
[0006] FIG. 1 illustrates ink dots ejected on a print medium P
using the conventional inkjet image forming apparatus of Japanese
Patent Laid-open Publication No. 2001-232781. FIG. 2 illustrates
ink dots ejected on another print medium P using the conventional
inkjet image forming apparatus. FIG. 3 illustrates ink dots ejected
on another print medium P using the conventional inkjet image
forming apparatus. In addition, FIG. 4 is an enlarged view of a
portion of a print region of the printing mediums P of FIGS. 2 and
3.
[0007] A printhead 20 having a plurality of nozzles N1 to NN
extending along a width of the print medium P in a direction that
is perpendicular to a print medium-feeding direction (X-direction)
is illustrated in FIG. 1. When the plurality of nozzles N1 to NN
are sequentially driven, a deviation degree W that corresponds to a
distance between a dot DD1 and a dot DDN is generated on the print
medium P Here, the deviation degree W is a difference between
positions of the dot DD1 ejected from a first nozzle N1 and the dot
DDN ejected from an N-th nozzle NN. As the deviation degree W
increases, ink is not ejected to a correct position and is ejected
further from the other ink dots such that an image quality is
lowered. The deviation degree W can be reduced using the following
methods: as illustrated in FIG. 2, ink is ejected by dividing a
plurality of head chips 21 into blocks so that each of the blocks
is placed in a reverse order (i.e., alternating between a first
direction and a second direction), or as illustrated in FIG. 3, ink
is ejected by disposing the plurality of head chips 21 in a zigzag
pattern so that each of the head chips 21 is placed in the reverse
order. Thus, when time-division driving is performed in the reverse
order, as illustrated in FIG. 4, the deviation degree W can be
reduced. However, two ink dots are ejected to a predetermined
region 10 and ink dots are not ejected to another region 30 so that
a blank region that corresponds to the region 30 exists. Thus, a
difference in optical density between the region 10 where ink dots
are ejected to overlap and the region 30 where ink dots are not
ejected occurs so that the image quality is lowered. This is a
problem in the conventional inkjet image forming apparatus that
attempts to print high quality images. Accordingly, an inkjet image
forming apparatus having an improved structure becomes
necessary.
SUMMARY OF THE INVENTION
[0008] The present general inventive concept provides an inkjet
image forming apparatus having an improved structure in which a
difference in deviation degree between ink dots generated by
time-division driving is minimized, thereby improving a printing
quality.
[0009] The present general inventive concept also provides an
inkjet image forming apparatus which improves a printing quality by
preventing regions printed to by adjacent nozzles from
overlapping.
[0010] Additional aspects of the present general inventive concept
will be set forth in part in the description which follows and, in
part, will be obvious from the description, or may be learned by
practice of the general inventive concept.
[0011] The foregoing and/or other aspects of the present general
inventive concept are achieved by providing an inkjet image forming
apparatus, the inkjet image forming apparatus including a printhead
having at least one nozzle group including a plurality of nozzles,
a driving unit to drive the plurality of nozzles to print an image,
and a controller to generate control signals to drive the driving
unit so as to drive the plurality of nozzles of the at least one
nozzle group and to time dimensionally drive the nozzles in the at
least one nozzle group in a plurality of nozzle blocks, wherein the
controller drives the nozzles of the at least one nozzle group and
the nozzles of the nozzle blocks in the same direction.
[0012] The inkjet image forming apparatus may further include a
carriage on which the printhead is mounted to move in a main
scanning direction and to print an image, wherein the printhead
prints to the same printed area moving two or more times
repeatedly.
[0013] The controller may generate control signals to determine an
order in which to drive the nozzles of the at least one nozzle
group and the nozzles of the nozzle blocks so that patterns printed
by driving the nozzles of the at least one nozzle group and
patterns printed by driving the nozzles of the nozzle blocks form
slanted lines having the same slope.
[0014] The controller may generate control signals so that the
patterns printed by driving the nozzles of the nozzle blocks are
symmetrical with one another based on the patterns printed by
driving the nozzles of the at least one nozzle group.
[0015] The controller may generate control signals so that the
nozzles of the at least one nozzle group are driven in one
direction when the printhead performs a first printing
operation.
[0016] The driving unit may include a thermal driving type driving
unit.
[0017] The driving unit may include a piezoelectric type driving
unit.
[0018] The nozzles of the at least one nozzle group may be disposed
to be parallel in a subsidiary scanning direction.
[0019] The at least one nozzle group may be disposed in a zigzag
pattern in a subsidiary scanning direction.
[0020] The foregoing and/or other aspects of the present general
inventive concept are also achieved by providing an inkjet image
forming apparatus, the inkjet image forming apparatus including at
least one nozzle group having a plurality of nozzles that are
arrangeable in two or more nozzle blocks, a printhead having the at
least one nozzle group, a driving unit to drive the nozzles to
print an image, and a controller to generate control signals to
drive the driving unit so as to drive the nozzles of the at least
one nozzle group and to drive the nozzles in the two or more nozzle
blocks time-divisionally, wherein the controller drives the nozzles
of the at least one nozzle group and the nozzles of the two or more
nozzle blocks in the same direction.
[0021] The inkjet image forming apparatus may further include a
carriage on which the printhead is mounted to move in a main
scanning direction and to print an image, wherein the printhead
prints to the same printed area moving two or more times
repeatedly.
[0022] The controller may generate control signals to sequentially
drive the nozzles of the at least one nozzle group from a first
nozzle to an N-th nozzle during a first printing operation, and to
drive one of the two or more nozzle blocks and then driving the
other of the two or more nozzle blocks during a second printing
operation.
[0023] The controller may generate control signals to determine an
order in which to drive the nozzles of the at least one nozzle
group and the nozzles of the two or more nozzle blocks so that
patterns printed during the first printing operation and patterns
printed during the second printing operation form slanted lines
having the same slope.
[0024] The foregoing and/or other aspects of the present general
inventive concept are also achieved by providing an inkjet image
forming apparatus, the inkjet image forming apparatus including a
first nozzle group having N nozzles, a second nozzle group disposed
to be parallel with the first nozzle group and having L nozzles, a
printhead having at least the first nozzle group and the second
nozzle group, a driving unit to drive the N nozzles and the L
nozzles to print an image, and a controller to generate control
signals to drive the driving unit so as to drive the nozzles N and
L of the first and second nozzle groups and to drive the N nozzles
and the L nozzles in a plurality of nozzle blocks
time-divisionally, wherein the controller drives the nozzles N and
L of the first and second nozzle groups and the nozzles of the
plurality of nozzle blocks in the same direction.
[0025] The inkjet image forming apparatus may further include a
carriage on which the printhead is mounted to move in a main
scanning direction and to print an image, wherein the printhead
prints to the same printed area moving two or more times
repeatedly.
[0026] The controller may generate control signals to drive the
driving unit so as to sequentially drive the nozzles N of the first
nozzle group from a first nozzle to an N-th nozzle, and to drive
the nozzles L of the second nozzle group in M nozzle blocks.
[0027] The controller may generate control signals to determine an
order in which to drive the nozzles N of the first nozzle group and
the nozzles L of the M nozzle blocks so that patterns printed by
driving the nozzles N of the first nozzle group and patterns
printed by driving the nozzles L of the M nozzle blocks form
slanted lines having the same slope.
[0028] The nozzles N and L of the first and second nozzle groups
may be disposed to be parallel in a subsidiary scanning
direction.
[0029] The first and second nozzle groups may be disposed in a
zigzag pattern in a subsidiary scanning direction.
[0030] The foregoing and/or other aspects of the present general
inventive concept are also achieved by providing an inkjet image
forming apparatus, comprising a print head unit having a plurality
of nozzles extending along a first axis thereof and to reciprocate
over a print medium, and a controller to control the print head
unit to perform a first printing operation to sequentially eject
ink from the plurality of nozzles in a line in a first direction
along the first axis, and to control the print head unit to perform
a second printing operation to sequentially eject ink from at least
a first block of the plurality of nozzles and at least a second
block of the plurality of nozzles in the line in the first
direction along the first axis.
[0031] The foregoing and/or other aspects of the present general
inventive concept are also achieved by providing an inkjet image
forming apparatus, comprising a print head unit having a plurality
of nozzles that are divisible into at least a first nozzle block
and a second nozzle block extending along a first axis thereof and
to reciprocate over a print medium, and a controller to control the
print head unit to perform a first printing operation to
sequentially eject ink from the first nozzle block and the second
nozzle block in a line in a first direction along the first axis,
and to control the print head unit to perform a second printing
operation to sequentially eject ink from the second nozzle block
and the first nozzle block in the line in the first direction along
the first axis.
[0032] The foregoing and/or other aspects of the present general
inventive concept are also achieved by providing an inkjet image
forming apparatus, comprising a print head unit having a plurality
of nozzles, and a controller to reciprocate the print head unit in
a predetermined reciprocation direction over a print medium, to
control the print head unit to perform a first print operation
using a first sequence of the plurality of nozzles in a
predetermined ejection direction, and to control the print head
unit to perform a second print operation using a second sequence of
the plurality of nozzles in the same predetermined ejection
direction.
[0033] The foregoing and/or other aspects of the present general
inventive concept are also achieved by providing an inkjet image
forming apparatus, comprising a print head unit including at least
a first nozzle group and a second nozzle group each having
corresponding pluralities of nozzles extending along a length of
the print head unit, and a controller to reciprocate the print head
unit over a print medium, to control the first nozzle group to
eject ink in a first sequence of the plurality of nozzles in a
predetermined sequence direction of the print head unit, to control
the second nozzle group to eject ink in a second sequence of the
corresponding plurality of nozzles in the predetermined sequence
direction of the print head unit, and the first sequence is
different from the second sequence.
[0034] The foregoing and/or other aspects of the present general
inventive concept are also achieved by providing a method of
controlling an inkjet image forming apparatus including a print
head unit having a plurality of nozzles, the method comprising
reciprocating the print head unit in a predetermined reciprocation
direction over a print medium, controlling the print head unit to
perform a first print operation using a first sequence of the
plurality of nozzles in a predetermined ejection direction, and
controlling the print head unit to perform a second print operation
using a second sequence of the plurality of nozzles in the same
predetermined ejection direction.
[0035] The foregoing and/or other aspects of the present general
inventive concept are also achieved by providing a method of
controlling an inkjet image forming apparatus including a print
head unit having a plurality of nozzles that are divisible into at
least a first nozzle block and a second nozzle block extending
along a first axis thereof and to reciprocate over a print medium,
the method comprising controlling the print head unit to perform a
first printing operation to sequentially eject ink from the first
nozzle block and the second nozzle block in a line in a first
direction along the first axis, and controlling the print head unit
to perform a second printing operation to sequentially eject ink
from the second nozzle block and the first nozzle block in the line
in the first direction along the first axis.
[0036] The foregoing and/or other aspects of the present general
inventive concept are also achieved by providing a computer
readable medium containing executable code to control an inkjet
image forming apparatus including a print head unit having a
plurality of nozzles, the method comprising a first executable code
to reciprocate the print head unit in a predetermined reciprocation
direction over a print medium, a second executable code to control
the print head unit to perform a first print operation using a
first sequence of the plurality of nozzles in a predetermined
ejection direction, and a third executable code to control the
print head unit to perform a second print operation using a second
sequence of the plurality of nozzles in the same predetermined
ejection direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] These and/or other aspects of the present general inventive
concept will become apparent and more readily appreciated from the
following description of the embodiments, taken in conjunction with
the accompanying drawings of which:
[0038] FIG. 1 illustrates ink dots ejected on a print medium using
a conventional inkjet image forming apparatus;
[0039] FIG. 2 illustrates ink dots ejected on another print medium
using the conventional image forming apparatus;
[0040] FIG. 3 illustrates ink dots ejected on another print medium
using the conventional image forming apparatus;
[0041] FIG. 4 is an enlarged view of a portion of a print region of
the print mediums of FIGS. 2 and 3;
[0042] FIG. 5 is a schematic view illustrating a scanning type
inkjet image forming apparatus according to an embodiment of the
present general inventive concept;
[0043] FIG. 6 is a view illustrating a printhead of the scanning
type inkjet image forming apparatus of FIG. 5 according to an
embodiment of the present general inventive concept;
[0044] FIG. 7 is a perspective view of a printhead unit and a
carriage moving unit of the scanning type inkjet image forming
apparatus of FIG. 5 according to an embodiment of the present
general inventive concept;
[0045] FIG. 8 is a block diagram illustrating operation of the
scanning type inkjet image forming apparatus according to another
embodiment of the present general inventive concept;
[0046] FIG. 9 illustrates the printhead of FIG. 6 according to an
embodiment of the present general inventive concept;
[0047] FIG. 10A illustrates print patterns printed when the
printhead of FIG. 9 performs a first scanning operation in one
direction according to an embodiment of the present general
inventive concept;
[0048] FIG. 10B illustrates print patterns printed when the
printhead of FIG. 9 performs a second scanning operation after the
first scanning operation of FIG. 10A according to an embodiment of
the present general inventive concept;
[0049] FIG. 11A illustrates print patterns printed when the
printhead of FIG. 9 performs a first scanning operation in another
direction according to another embodiment of the present general
inventive concept;
[0050] FIG. 11B illustrates print patterns printed when the
printhead of FIG. 9 performs a second scanning operation after the
first scanning operation of FIG. 11A according to another
embodiment of the present general inventive concept;
[0051] FIG. 12 illustrates a printhead according to another
embodiment of the present general inventive concept;
[0052] FIG. 13 illustrates print patterns printed when the
printhead of FIG. 12 performs a scanning operation in one direction
according to an embodiment of the present general inventive
concept;
[0053] FIG. 14 illustrates print patterns printed when the
printhead of FIG. 12 performs a scanning operation in another
direction according to an embodiment of the present general
inventive concept; and
[0054] FIGS. 15A and 15B illustrate a printhead according to other
embodiments of the present general inventive concept.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0055] Reference will now be made in detail to the embodiments of
the present general inventive concept, examples of which are
illustrated in the accompanying drawings, wherein like reference
numerals refer to the like elements throughout. The embodiments are
described below in order to explain the present general inventive
concept by referring to the figures.
[0056] FIG. 5 is a schematic view illustrating a scanning type
inkjet image forming apparatus according to an embodiment of the
present general inventive concept. Referring to FIG. 5, the
scanning type inkjet image forming apparatus includes a paper
feeding cassette 120, a printhead unit 105, a support member 114
that faces the printhead unit 105, a plurality of print
medium-feeding units 113, 115, 116, and 117 that feed a print
medium P in a subsidiary scanning direction, and a stacking unit
140 on which a discharged print medium P is stacked.
[0057] The print medium P is stacked on the paper feeding cassette
120. The print medium P stacked on the paper feeding cassette 120
is fed to a printhead 111 by the print medium-feeding units 113,
115, 116, and 117, which are described below. In FIG. 5, the print
medium P is fed in an x-direction, which is the subsidiary scanning
direction, and the printhead 111 moves in a y-direction, which is a
main scanning direction. The subsidiary scanning direction and the
main scanning direction may be perpendicular to each other.
Alternatively, the subsidiary scanning direction and the main
scanning direction may be inclined at a predetermined angle with
respect to each other.
[0058] The print medium-feeding units 113, 115, 116, and 117 feed
the print medium P that is stacked on the paper feeding cassette
120 along a predetermined path. In FIG. 5, the print medium-feeding
units 113, 115, 116, and 117 include a pickup roller 117, a feeding
roller 115, and a paper discharging roller 113. The print
medium-feeding units 113, 115, 116, and 117 are driven by a driving
source 131 such as a motor and provide a force to feed the print
medium P. Operation of the driving source 131 is controlled by a
controller 130, which is described below.
[0059] The pickup roller 117 is installed at one side of the paper
feeding cassette 120 and picks up the print medium P that is
stacked on the paper feeding cassette 120 one by one, thereby
withdrawing the print medium P from the paper feeding cassette 120.
The pickup roller 117 is rotated while pressing a top side of the
print medium P, thereby feeding the print medium P outside of the
paper feeding cassette 120.
[0060] The feeding roller 115 is installed at an inlet side of the
printhead 111 and feeds the print medium P withdrawn by the pickup
roller 117 to the printhead 111. In this case, the feeding roller
115 can align the print medium P so that ink can be ejected onto a
desired portion of the print medium P, before the print medium P is
transferred to the printhead 111. The feeding roller 115 includes a
driving roller 11 5A that provides a feeding force to feed the
print medium P and an idle roller 115B elastically engaged with the
driving roller 115A. An auxiliary roller 116 that feeds the print
medium P can be further installed between the pickup roller 117 and
the feeding roller 115.
[0061] The paper discharging roller 113 is installed at an outlet
side of the printhead 111 and discharges the print medium P on
which a printing operation has been completed, outside of the
scanning type image forming apparatus. The print medium P that is
discharged outside of the scanning type image forming apparatus is
stacked on the stacking unit 140. The paper discharging roller 113
includes a star wheel 113A installed in a widthwise direction along
the print medium P and a support roller 113B that faces the star
wheel 11 3A and supports a rear side of the print medium P. The
print medium P includes a top side having wet ink that is ejected
by the printhead 111, which reciprocates along the main scanning
direction. The print medium P may wrinkle before it is transferred
past the printhead 111. If the wrinkling is severe, the print
medium P contacts a nozzle unit 112 or a bottom surface of a body
110, undried ink is spread (i.e., smeared) on the print medium P,
and an image printed thereon may be contaminated. In addition, due
to the wrinkling, there is a high probability that a distance
between the print medium P and the nozzle unit 112 may not be
maintained. The star wheel 113A is used to prevent the print medium
P fed in a downward direction of the nozzle unit 112 from
contacting the nozzle unit 112 or the bottom surface of the body
110, and to prevent the distance between the print medium P and the
nozzle unit 112 from varying. At least a part of the star wheel
113A is installed to protrude further downward than in the nozzle
unit 112 and makes point contact with the top side of the print
medium P. According to the above structure, the star wheel 113A
makes point contact with the top side of the print medium P so that
an ink image that has been ejected on the top side of the print
medium P, and has not yet dried, is prevented from being
contaminated. In addition, a plurality of star wheels may be
installed so as to feed the print medium P smoothly. When the
plurality of star wheels are installed to be parallel to a feeding
direction of the print medium P, a plurality of support rollers
that correspond to the plurality of star wheels may be
provided.
[0062] In addition, when the printing operation is consecutively
performed on a plurality of sheets of the print medium P, the print
medium P is discharged and stacked on the stacking unit 140 and
then, a next print medium P is discharged before ink ejected on the
top side of the print medium P is dried, and a rear side of the
next print medium P may be contaminated. To prevent this potential
problem, an additional drying device (not shown) may be further
provided.
[0063] The support member 114 is disposed below the printhead 111
so that a predetermined distance between the nozzle unit 112 and
the print medium P can be maintained, and supports the rear side of
the print medium P. The distance between the nozzle unit 112 and
the print medium P may be about 0.5-2.5 mm.
[0064] A sensing unit 132 senses whether or not a defective nozzle
exists in the nozzle unit 112 disposed under the printhead 111.
Here, the defective nozzle may be a damaged nozzle or a weak nozzle
that cannot eject ink properly. That is, the defective nozzle
occurs when ink is not ejected from nozzles due to a variety of
causes or when a smaller amount of ink droplet is ejected.
[0065] The sensing unit 132 includes a first sensing unit 132A that
senses whether or not a defective nozzle exists in the nozzle unit
112 before the printing operation starts and a second sensing unit
132B that senses whether or not a defective nozzle exists in the
nozzle unit 112 while the printing operation is performed. The
first sensing unit 132A senses whether or not nozzles are clogged
by radiating light directly onto the nozzle unit 112, and the
second sensing unit 132B senses whether or not a defective nozzle
exists in the nozzle unit 112 by radiating light onto the print
medium P that is being fed.
[0066] The second sensing unit 132B may be an optical sensor
including a light-emitting sensor such as a light emitting diode
that radiates light onto the print medium P and a light-receiving
sensor that receives light reflected from the print medium P The
light-emitting sensor and the light-receiving sensor may be formed
as a single body or in a separate shape. The structure and
operation of the optical sensor should be known to those skilled in
the art, and thus, a detailed description thereof will not be
provided.
[0067] The printhead unit 105 prints an image by ejecting ink onto
the print medium P The printhead unit 105 includes the body 110,
the printhead 111 disposed on the bottom surface of the body 110,
the nozzle unit 112 disposed under the printhead 111, and a
carriage 106 on which the body 110 is mounted to reciprocate in the
main scanning direction (i.e., the y-direction). The body 110
having the printhead 111 is mounted in a cartridge shape on the
carriage 106, and a carriage moving unit 142 (see FIG. 6), which is
described below, and reciprocates the carriage 106 in the main
scanning direction. The feeding roller 115 is installed at the
inlet side of the nozzle unit 112, and the paper discharging roller
113 is installed at the outlet side of the nozzle unit 112. In
addition, a cable transmits a driving signal generated by the
controller 130, which is described below, including power to eject
ink, print data, or the like to nozzles of the nozzle unit 112. In
this case, a flexible cable such as a flexible printed circuit
(FPC) or a flexible flat cable (FFC) may be used.
[0068] FIG. 6 is a view illustrating the printhead 111 of the
scanning type image forming apparatus of FIG. 5 according to an
embodiment of the present general inventive concept. In FIG. 6,
reference numerals N1, N2, N3, N4, . . . , and NN represent the
nozzles, reference numeral NG represents a nozzle group, and
reference numerals M1, M2, . . . , and MM represent nozzles divided
into blocks in each nozzle group.
[0069] Referring to FIG. 6, the printhead 111 includes N nozzle
units 112 disposed in the subsidiary scanning direction (i.e., the
x-direction). The printhead 111 prints an image by ejecting ink
onto the print medium P while making a reciprocating motion in the
main scanning direction (i.e., the y-direction). The printhead 111
uses thermal energy, a piezoelectric device, or the like as a power
source to eject the ink, and the printhead 111 is manufactured to
have a high resolution using a semiconductor manufacturing
processes such as etching, deposition, and sputtering, and the
like. The printhead 111 may eject one color or two or more
colors.
[0070] The nozzle unit 112 includes at least one nozzle group NG. N
nozzles N1, N2, N3, N4, . . . , and NN to print an image by
ejecting ink onto the print medium P are disposed in each nozzle
group NG. N nozzles N1, N2, N3, N4, . . . , and NN in each nozzle
group NG are divided into M blocks M1, M2, . . . , and MM so that
time-division driving can be performed. That is, the N nozzles N1,
N2, N3, N4, . . . , and NN and the M blocks M1, M2, . . . , and MM
of each nozzle group NG are time-divisionally driven independently
by a driving unit 150 that is described below. Here, a number of
nozzles of each nozzle group NG and a number of nozzles of the M
blocks may be different. In addition, although the nozzle unit 112
illustrated in FIG. 6 includes the N nozzles N1, N2, N3, N4, . . .
, and NN arranged in a straight line, it should be understood that
the N nozzles N1, N2, N3, N4, . . . , and NN may be arranged in a
zigzag pattern in two or more lines so as to improve the
resolution.
[0071] Although not shown, a storage space in which ink is to be
stored is disposed in the body 110. An ink-storing space is formed
in a cartridge shape in the body 110 to be attachable and
detachable therefrom. The body 110 may further include a chamber
having the driving unit 150 in communication with each of nozzles
N1, N2, N3, N4, . . . , and NN of the nozzle unit 112 and to apply
pressure to eject the ink (e.g., piezoelectric device and a thermal
driving heater) a passage such as an orifice to supply ink received
in the body 110 to the chamber, a manifold that is a common passage
to supply ink that flows in via the passage to the chamber, and a
restrictor which is a separate passage to supply ink to each
chamber from the manifold, and/or the like. The chamber, the
passage, the manifold, the restrictor, and the like should be known
to those skilled in the art, and thus, a detailed description
thereof will not be provided.
[0072] The driving unit 150 supplies an ejecting force and
time-divisionally drives the N nozzles N1, N2, N3, . . . , and NN
of each nozzle group NG and the N nozzles N1, N2, N3, . . . , and
NN-may be divided into the M blocks M1, M2, . . . , and MM and
driven, thereby printing an image. The driving unit 150 may be
classified according to a type of actuator that supplies the
ejecting force to the ink droplets. The driving unit 150 may be a
thermal driving type that generates bubbles in the ink using a
heater to eject the ink droplets using an expansion force of the
bubbles, or a piezoelectric device type that ejects the ink
droplets using pressure applied to the ink due to deformation of a
piezoelectric device. As described above, the driving unit 150
selectively drives the N nozzles N1, N2, N3, N4, . . . , and NN and
the M blocks M1, M2, . . . , and MM, thereby printing the image. In
this case, the ejecting operation of the nozzle unit 112, that is,
the ejecting operations of the N nozzles N1, N2, N3, N4, . . . ,
and NN and the M blocks M1, M2, . . . , and MM are controlled by
the controller 130, which is described below.
[0073] FIG. 7 is a perspective view of the printhead unit 105 and
the carriage moving unit 142 of the scanning type image forming
apparatus of FIG. 5 according to an embodiment of the present
general inventive concept. Referring to FIGS. 5 and 7, the body 110
is mounted on the carriage 106. The printhead 111 is mounted on the
carriage 106 in a cartridge shape connected to the body 110. The
carriage moving unit 142 allows the carriage 106 to make a
reciprocating motion in the main scanning direction and includes a
carriage moving motor 144, carriage moving rollers 143a and 143b,
and a carriage moving belt 145. A power from a main body of the
scanning type image forming apparatus is supplied to the carriage
moving motor 144. One side of each of the carriage moving rollers
143a and 143b is connected to the carriage moving motor 144, and
the other side thereof is installed on a main frame (not shown).
The carriage moving belt 145 is supported by the carriage moving
rollers 143a and 143b and is transferred therearound, endlessly.
The carriage 106 is combined with the carriage moving belt 145. The
carriage 106 moves to a predetermined position in response to a
control signal transmitted from the controller 130, which is
described below, to the carriage moving motor 144. The
reciprocating motion of the carriage 106 is guided by a guide shaft
108. The guide shaft 108 guides the reciprocating motion of the
carriage 106 driven by the carriage moving motor 144. A combining
unit 107, into which the guide shaft 108 is inserted, is disposed
at one side of the carriage 106. The combining unit 107 is
perforated at one side of the carriage 106. The guide shaft 108 is
inserted into the combining unit 107 that is formed in a hollow
shape and guides the reciprocating motion of the carriage 106.
[0074] FIG. 8 is a block diagram illustrating operation of the
scanning type inkjet image forming apparatus of FIG. 5 according to
another embodiment of the present general inventive concept.
[0075] Referring to FIGS. 5 to 8, a data inputting unit 135 is a
host system such as a personal computer (PC), a digital camera, or
a personal digital assistant (PDA). Image data to be printed is
input to the data inputting unit 135 in an order that corresponds
to pages to be printed. The data inputting unit 135 includes an
application program, a graphics device interface (GDI), an image
forming apparatus driver, a user interface, and a spooler.
[0076] The scanning type image forming apparatus includes a video
controller (not shown) and the controller 130. The video controller
interprets and bitmaps commands generated by the image forming
apparatus driver, and then transmits the interpreted commands to
the controller 130. The controller 130 transmits the bitmap
generated by the video controller to each element of the scanning
type image forming apparatus, thereby forming an image on the print
medium P. The printing operation is then performed in the scanning
type image forming apparatus using the above-described
procedure.
[0077] Referring to FIG. 8, the controller 130 may be disposed on a
motherboard of the scanning type image forming apparatus and
controls an ejecting operation of the nozzle unit 112 disposed
under the printhead 111, an operation of the print medium-feeding
units 113, 115, 116, and 117 (see FIG. 5), and an operation of the
carriage 106 (see FIGS. 5 and 7). That is, the controller 130
synchronizes the operation of each element of the scanning type
image forming apparatus so that ink is ejected from the nozzle unit
112 that moves in the main scanning direction when the printing
operation to a predetermined portion of the print medium P with a
predetermined resolution. The controller 130 stores the image data
input through the data inputting unit 135 in a memory 137 and
checks whether the image data to be printed has been completely
stored in the memory 137.
[0078] If the image data has been completely stored, the controller
130 operates the driving source 131 by generating a control signal
that corresponds to a printing environment. The print medium P is
fed by the print medium-feeding units 113, 115, 116, and 117 (see
FIG. 5) that are driven by the driving source 131. The print medium
P that is withdrawn by the pickup roller 117 is transferred to the
nozzle unit 112. The controller 130 moves the printhead 111 in the
main scanning direction, thereby printing an image.
[0079] The controller 130 generates control signals to control the
ejecting operation of the nozzle unit 112, and the nozzle unit 112
prints the image data on the print medium P in response to the
control signals. That is, as illustrated in FIG. 6, the controller
130 controls the driving unit 150 and time-divisionally drives the
N nozzles N1, N2, N3, . . . , and NN of each nozzle group NG, and
the N nozzles N1, N2, N3, . . . , and NN divided into the M blocks
M1, M2, . . . , and MM are driven. In this case, the controller 130
drives the N nozzles N1, N2, N3, . . . , and NN of each nozzle
group NG and the N nozzles N1, N2, N3, . . . , and NN divided into
the M blocks M1, M2, . . . , and MM in the same direction (as
opposed to the conventional inkjet image forming apparatus
described with reference to FIGS. 1 to 4). In addition, the
controller 130 controls the operation of the printhead 111 so that
the printhead 111 prints to the same printed area by moving two or
more times repeatedly over the printed area.
[0080] In order to minimize a difference in a deviation degree
generated by time-division driving and to prevent a printed area
printed to by a nozzle from overlapping with a printed area printed
to by an adjacent nozzle, the controller 130 generates control
signals to determine an order in which to drive the nozzles of the
nozzle group NG and the nozzles of the M blocks M1, M2, . . . , and
MM so that patterns printed by driving the nozzles of the nozzle
group NG and patterns printed by driving the nozzles of the M
blocks M1, M2, . . . , and MM form a slanted line having the same
slope. In this case, the controller 130 may generate the control
signals so that the patterns printed by driving the nozzles of the
M blocks M1, M2, . . . , and MM are symmetrical with one another
based on the patterns printed by driving the nozzles of the nozzle
group NG. Alternatively, the controller 130 may generate the
control signals to drive the nozzles of the nozzle group NG in one
direction and to print when the printhead 111 performs a printing
operation for the first time.
[0081] Print patterns according to an embodiment of the present
general inventive concept will now be described in order to
illustrate the various embodiments of the present general inventive
concept. A case in which one nozzle group including N nozzles is
time-divisionally driven into two blocks will be described first.
In addition, the printhead 111 prints to the same print area
twice.
[0082] FIG. 9 illustrates the printhead 111 of FIG. 6 according to
an embodiment of the present general inventive concept, FIG. 10A
illustrates print patterns printed when the printhead 111 of FIG. 9
performs a first scanning operation in one direction, and FIG. 10B
illustrates print patterns printed when the printhead 111 of FIG. 9
performs a second scanning operation after the first scanning
operation of FIG. 10A. In addition, FIG. 11A illustrates print
patterns printed when the printhead 111 of FIG. 9 performs a first
scanning operation in another direction, and FIG. 11B illustrates
print patterns printed when the printhead 111 performs a second
scanning operation after the first scanning operation of FIG.
11A.
[0083] Referring to FIG. 9, the nozzle unit 112 includes one nozzle
group NG. The nozzle group NG includes 16 nozzles, and the 16
nozzles are time-divisionally driven as a first block M1 and a
second block M2. The first block M1 includes first to eighth
nozzles N1 to N8, and the second block M2 includes ninth to
sixteenth nozzles N9 to N16. Although FIG. 9 illustrates that the
nozzle unit 112 has one nozzle group NG with two blocks Ml and M2,
each including eight nozzles, it should be understood that the
nozzle unit 112 may have a variety of other arrangements including
any number of nozzle groups, blocks, and/or nozzles. In addition,
the printhead 111 moves in the main scanning direction (i.e.,
y-direction), prints an image, prints to the same print area at
least twice, repeatedly. In this case, the print medium P may be
fed under the nozzle unit 112 and stopped under the nozzle unit
112, repeatedly.
[0084] As illustrated in FIG. 10A, the controller 130 sequentially
drives the first nozzle N1 to sixteenth nozzle N16 of the nozzle
group NG in a direction of arrow A when the first printing
operation is performed (i.e., during the first scanning operation).
Since the printhead 111 moves along the main scanning direction
(i.e., the y-direction) and ejects ink droplets onto the stopped
print medium P, ink dots IF1 that are ejected onto the print medium
P are formed along a slanted line having a predetermined slope. If
the first scanning operation has been completely performed, the
printhead 111 moves to its original location (e.g. at a left side
of the print medium P). As illustrated in FIG. 10B, the controller
130 drives at least one of the two blocks M1 and M2 and then drives
the other block when the second printing operation is performed
(i.e., during the second scanning operation). In the present
embodiment, the second block M2 is driven first and then the first
block M1 is driven second. That is, the controller 130 sequentially
drives the ninth nozzle N9 to the sixteenth nozzle N16 of the
second block M2 in a direction of arrow B, and then sequentially
drives the first nozzle N1 to the eighth nozzle. N8 of the first
block M1 in a direction of arrow C. Thus, ink dots IF2 that are
ejected onto the print medium P by the second block M2 during the
second printing operation and ink dots IF3 that are ejected onto
the print medium P by the first block M1 during the second printing
operation are formed along a slanted line having a predetermined
slope. In this case, the controller 130 may drive the nozzle group
NG and the two blocks M1 and M2 so that the ink dots IF1 ejected
during the first printing operation and the ink dots IF2 and IF3
ejected during the second printing operation form a slanted line
having the same slope, as illustrated in FIG. 10B. The controller
130 feeds the print medium P by a predetermined distance before
printing to a next region, and then repeatedly performs the
above-described operations, thereby printing an image. If the
nozzle group NG and the two blocks M1 and M2 are driven using the
above-described operations, a difference in a deviation degree W
that occurs by time-division driving can be visually minimized and
ink dots ejected by adjacent nozzles can be prevented from
overlapping. In other words, all the nozzles N1 to N16 can be used
in a first printing operation while the printhead 111 moves in the
y-direction (left to right), then the second block M2 can be driven
before the first block M1 during the second printing operation
while the printhead 111 moves again in the y-direction (left to
right). Accordingly, the printhead 111 moves in the y-direction
over the same print area twice without overlapping ink
ejections.
[0085] Referring to FIGS. 11A and 11B, the controller 130
sequentially drives the sixteenth nozzle N16 to the first nozzle N1
of the nozzle group NG in a direction of arrow a when the first
printing operation is performed (i.e., during the first scanning
operation). Since the printhead 111 moves in the main scanning
direction (i.e., the y-direction) and ejects ink droplets onto the
stopped print medium P, ink dots 1B1 ejected onto the print medium
P are formed along a slanted line having a predetermined slope. If
the first scanning operation has been completely performed, the
printhead 111 moves to its original location (e.g. at a left side
of the print medium P). As illustrated in FIG. 11B, the controller
130 drives one of two blocks M1 and M2 and then drives the other
block when the second printing operation is performed (i.e., during
the second scanning operation). In the present embodiment, the
first block M1 is driven and then the second block M2 is driven.
That is, the controller 130 sequentially drives the eighth nozzle
N8 to the first nozzle N1 of the first block M1 in a direction of
arrow b, and then sequentially drives the sixteenth nozzle N16 to
the ninth nozzle N9 of the second block M2 in a direction of arrow
c (i.e., the same direction as the arrow b). Thus, ink dots 1B2
ejected onto the print medium P by the first block M1 during the
second printing operation and ink dots 1B3 ejected onto the print
medium P by the second block M2 during the second printing
operation are formed along a slanted line having the predetermined
slope. In this case, the controller 130 may drive the entire nozzle
group NG and the two blocks M1 and M2 so that the ink dots 1B1
ejected during the first printing operation and the ink dots 1 B2
and 1 B3 ejected during the second printing operation form a
slanted line having the same slope, as illustrated in FIG. 11B. The
controller 130 then feeds the print medium P by the predetermined
distance before printing to the next region, and then repeatedly
performs the above-described operations, thereby printing an image.
If the entire nozzle group NG and the two blocks M1 and M2 are
driven using the above-described operations, a difference in the
deviation degree W that occurs by time-division driving can be
visually minimized and ink dots ejected by adjacent nozzles can be
prevented from overlapping. The controller 130 controls the
printhead 111 to reciprocate in the y-direction along the print
medium P (e.g. left to right) two times, one time for each printing
operation. Accordingly, the printhead 111 moves over the same print
area twice without overlapping ink ejections. It should be
understood that more than two printing operations may alternatively
be performed. In this case, the printhead 111 may reciprocate over
the same print area more than two times.
[0086] FIG. 12 illustrates a printhead 111' according to another
embodiment of the present general inventive concept. In FIG. 12,
reference numeral NG1 represents a first nozzle group, reference
numeral NG2 represents a second nozzle group, reference numerals
N1, N2, N3, N4, . . . , and NN represent nozzles of the first
nozzle group NG1, reference numerals L1, L2, L3, L4, . . . , and LL
represent nozzles of the second nozzle group NG2, and reference
numerals M1, . . . , and MM represent nozzles divided into blocks
in the second nozzle group NG2. The structure and operation of the
present embodiment are similar to those of the printhead 111 of
FIGS. 6 through 11, and thus, some of the description thereof will
not be provided. In addition, similar components of the printheads
111 and 111' are represented using like reference numerals. The
structure and operation of the first nozzle group NG1 and the
second nozzle group NG2 may be reversed.
[0087] Referring to FIG. 12, the printhead 111' includes a nozzle
unit 112' disposed in a subsidiary scanning direction (i.e., an
x-direction). The printhead 111' prints an image by ejecting ink
onto the print medium P while making a reciprocating motion in a
main scanning direction (i.e., y-direction). The nozzle unit 112'
includes at least one first nozzle group NG1 and a second nozzle
group NG2 disposed to be parallel to the first nozzle group NG1. N
nozzles N1, N2, N3, N4, . . . , and NN to print an image by
ejecting ink onto the print medium P are disposed in the first
nozzle group NG1, and L nozzles L1, L2, L3, L4, . . . , and LL are
disposed in the second nozzle group NG2. In addition, the first and
second nozzle groups NG1 and NG2 may be divided into a plurality of
blocks. Here, a number of nozzles of the first nozzle group NG1 and
a number of nozzles of the second nozzle group NG2 may be the same.
In addition, although the nozzles N1, N2, N3, N4, . . . , and NN of
the first nozzle group NG1 and the nozzles L1, L2, L3, L4, . . . ,
and LL of the second nozzle group NG2 illustrated in FIG. 12 are
disposed to be parallel in a straight line, it should be understood
that the nozzles of the first and second nozzle groups NG1 and NG2
may alternatively be disposed in a zigzag pattern so as to improve
a resolution.
[0088] The controller 130 time-divisionally drives the N nozzles
N1, N2, N3, . . . , and NN of the first nozzle group NG1, the L
nozzles L1, L2, L3, . . . , and LL of the second nozzle group NG2,
and the plurality of blocks M1 to MM. In this case, an order in
which to drive the nozzles of the first and second nozzle groups
NG1 and NG2 and an order in which to drive the plurality of nozzles
is in the same direction (as opposed to the conventional inkjet
image forming apparatus described with reference to FIGS. 1 to 4).
In addition, the controller 130 controls the operation of the
printhead 111' so as to print to the same print area by moving in
the y-direction one or more times, repeatedly.
[0089] The controller 130 may time-divisionally drive the L nozzles
L1, L2, L3, L4, . . . , and LL of the second nozzle group NG2 into
M blocks M1, . . . , and MM. In order to minimize a difference in a
deviation degree generated by the time-division driving and to
prevent ink ejected from a nozzle from overlapping with ink ejected
by an adjacent nozzle, the controller 130 may sequentially drive
the nozzles of the first nozzle group NG1 from the first nozzle N1
to the N-th nozzle NN and may drive the nozzles of the second
nozzle group NG2 in M blocks time-divisionally. For example, the
controller 130 may generate a control signal to determine the order
in which to drive nozzles of the first nozzle group NG1 and nozzles
of the M blocks M1, M2, . . . , and MM so that patterns that are
printed by driving the nozzles of the first nozzle group NG1 and
patterns that are printed by driving the nozzles of the M blocks
M1, M2, . . . , and MM form a slanted line having the same
slope.
[0090] Print patterns according to another embodiment of the
present general inventive concept will now be described.
[0091] FIG. 13 illustrates print patterns printed when the
printhead 111' of FIG. 12 performs a scanning operation in one
direction, and FIG. 14 illustrates print patterns printed when the
printhead 111' of FIG. 12 performs a scanning operation in another
direction. The first and second nozzle groups NG1 and NG2 include
16 nozzles, and the second nozzle group NG2 is time-divisionally
driven as the first block M1 and the second block M2. The first
block M1 may include the first nozzle L1 to the eighth nozzle L8,
and the second block M2 may include the ninth nozzle L9 to the
sixteenth nozzle L6. It should be understood that this description,
however, is not intended to limit the arrangements of nozzles in
the nozzle unit 112'. Other arrangements of nozzles may
alternatively be used in the printhead 111'. In addition, the
printhead 111' moves in the main scanning direction (i.e.,
y-direction), prints an image, and prints to the same print area
once. Since the printhead 111' has two nozzle groups, the printhead
111' can achieve similar results obtained with the printhead 111 of
FIG. 9, without reciprocating over the same print area more than
once. After a printing operation in a predetermined area has been
completely performed, the print medium P is repeatedly fed and
stopped.
[0092] Referring to FIG. 13, the controller 130 time-divisionally
drives the first nozzle group NG1 and the second nozzle group NG2.
That is, the controller 130 sequentially drives the first nozzle N1
to the sixteenth nozzle N16 of the first nozzle group NG1. Since
the printhead 111 moves in the main scanning direction (i.e.,
y-direction) and ejects ink droplets onto the stopped print medium
P, ink dots 1F1 ejected onto the print medium P are formed along a
slanted line having a predetermined slope. In addition, the
controller 130 drives one of two blocks M1 and M2 of the second
nozzle group NG2 and then drives the other block. In the present
embodiment, the first nozzle group NG1 and the second nozzle group
NG2 may be driven simultaneously in one printing operation. In the
present embodiment, the second block M2 is driven and then the
first block M1 is driven. That is, the controller 130 sequentially
drives the ninth nozzle L9 to the sixteenth nozzle L16 of the
second block M2 in a direction of arrow B, and then sequentially
drives the first nozzle L1 to the eighth nozzle L8 of the first
block M1 in a direction of arrow C. Thus, ink dots 2F1 ejected onto
the print medium P by the second block M2 and ink dots 2F2 ejected
onto the print medium P by the first block M1 are formed along a
slanted line having the predetermined slope. In this case, the
controller 130 may drive the first nozzle group NG1 and the second
nozzle group NG2 so that the ink dots 1F1 by time-division driving
of the first nozzle group NG1 and the ink dots 2F1 and 2F2 by
time-division driving of the second nozzle group NG2 form a slanted
line having the same slope, as illustrated in FIG. 13. The
controller 130 feeds the print medium P by a predetermined distance
before printing to a next region and then repeatedly performs the
above-described operations, thereby printing an image. If the first
nozzle group NG1 and the second nozzle group NG2 are driven using
the above-described operations, a difference in a deviation degree
W produced by time-division driving can be visually minimized and
the ink dots ejected by adjacent nozzles can be prevented from
overlapping.
[0093] Referring to FIG. 14, the controller 130 drives the first
nozzle group NG1 and the second nozzle group NG2 in a direction
opposite to the direction illustrated in FIG. 13. That is, the
controller 130 sequentially and time-divisionally drives the
sixteenth nozzle N16 to the first nozzle N1 of the first nozzle
group NG1 in a direction of arrow d. Since the printhead 111' moves
in the main scanning direction (i.e., the y-direction) and ejects
the ink droplets onto the stopped print medium P, ink dots 1B1
ejected onto the print medium P are formed along a slanted line
having the predetermined slope. In addition, the controller 130
drives one of two blocks M1 and M2 of the second nozzle group NG2
and then drives the other block. Again, the first nozzle group NG1
and the second nozzle group NG2 may be driven simultaneously in one
printing operation. In the present embodiment, the first block M1
is driven and then the second block M2 is driven. That is, the
controller 130 sequentially drives the eighth nozzle L8 to the
first nozzle L1 of the first block M1 in a direction of arrow e,
and then sequentially drives the sixteenth nozzle L16 to the ninth
nozzle L9 of the first block M1 in a direction of arrow f. Thus,
ink dots 2B1 ejected onto the print medium P by the second block M2
and ink dots 2B2 ejected onto the print medium P by the first block
M1 are formed along a slanted line having the predetermined slope.
In this case, the controller 130 may drive the first nozzle group
NG1 and the second nozzle group NG2 so that the ink dots 1B1
ejected by time-division driving of the first nozzle group NG1 and
the ink dots 2B1 and 2B2 ejected by time-division driving of the
second nozzle group NG2 form a slanted line having the same slope,
as illustrated in FIG. 14. The controller 130 feeds the print
medium P by the predetermined distance before printing to the next
region and then repeatedly performs the above-described operations,
thereby printing an image. If the first nozzle group NG1 and the
second nozzle group NG2 are driven using the above-described
operations, a difference in a deviation degree W produced by
time-division driving can be visually minimized and the ink dots
ejected by adjacent nozzles can be prevented from overlapping.
[0094] FIGS. 15A and 15B illustrate printheads 111'' and 111'''
according to other embodiments of the present general inventive
concept. For illustration purposes, like reference numerals are
used to refer to elements having the same functions as those
elements illustrated in FIGS. 6 through 11. In the printhead 111''
of FIG. 15A, four nozzle groups NG1, NG2, NG3, and NG4 are arranged
in a zigzag pattern in the subsidiary scanning direction. In the
printhead 111''' of FIG. 15B, nozzles of the nozzle group NG1 are
disposed to be parallel in the subsidiary scanning direction. Here,
reference numerals 112C, 112M, 112Y, and 112K represent nozzle rows
to eject cyan, magenta, yellow, and black ink, respectively. It
should be understood that arrangements of the nozzles in the
printheads 111'' and 111''' of FIGS. 15A and 15B are exemplary and
are not intended to limit the scope of the present general
inventive concept, and other arrangements may alternatively be
used.
[0095] The embodiments of the present general inventive concept can
be embodied as computer readable codes on a computer readable
recording medium. The computer readable recording medium may
include any data storage device that can store data which can be
thereafter read by a computer system. Examples of the computer
readable recording medium include a read-only memory (ROM), a
random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks,
optical data storage devices, and carrier waves (such as data
transmission through the Internet). The computer readable recording
medium can also be distributed over network coupled computer
systems so that the computer readable code is stored and executed
in a distributed fashion. The embodiments of the present general
inventive concept may also be embodied in hardware or a combination
of hardware and software. For example, the controller 130 may be
embodied in software, hardware, or a combination thereof.
[0096] According to the above-described structures and operations,
a difference in a deviation degree produced by time-division
driving can be visually minimized and ink dots ejected by adjacent
nozzles can be prevented from overlapping.
[0097] As described above, in an inkjet image forming apparatus
according to various embodiments of the present general inventive
concept, nozzle groups and nozzle groups divided into blocks are
time-divisionally driven in the same direction so that a difference
in a deviation degree produced by time-division driving can be
minimized and quality of a printed image can be improved. In
addition, the nozzle groups and the nozzle groups divided into
blocks are time-divisionally driven in the same direction such that
a double-printed area or an unprinted area are not formed, and ink
is uniformly ejected onto the print medium such that printing
quality can be improved.
[0098] Although a few embodiments of the present general inventive
concept have been shown and described, it will be appreciated by
those skilled in the art that changes may be made in these
embodiments without departing from the principles and spirit of the
general inventive concept, the scope of which is defined in the
appended claims and their equivalents.
* * * * *